1 . Field of the Invention
The present invention relates to a diaphragm, and more particularly to a diaphragm pump for effectively preventing pulsation of liquid by installing an air chamber on the side wall of the pump head, which is connected to a head-side discharge hole of the diaphragm pump and includes a discharge-side discharge hole.
2 . Description of the Prior Art
Generally, a typical diaphragm pump pumps liquid by converting rotational movement of a motor into a reciprocating movement by devices such as a cam. Since the amount of the discharged liquid from the diaphragm pump fluctuates by very small volume, the diaphragm pump is generally used for precisely instilling liquid chemicals or medicines.
FIGS. 1A to 1E are cross sectional views illustrating one embodiment of a conventional diaphragm pump. As shown in FIG. 1A, a diaphragm 110 is supported by a support ring 120 to form a pump chamber 130 in an opening area of a pump head 100. A suction hole 105 and a discharge hole 106 are located at the upper portion and the lower portion of a body 102, respectively.
The suction hole 105 and the discharge hole 106 are opened/closed by a check ball 140. Referring to FIG. 1C, an opening-side valve seat 141 having a cross-shaped groove is formed on a suction end of the suction hole 105 of the pump head 100 and an end of a discharge-side connector 160. And, a closing-side valve seat 142 having tapered shape is formed at an end of a suction connector 150 and a discharge side of the discharge hole 106 of the pump head 100.
The following describes the operation of the diaphragm pump constructed in such a manner as mentioned above.
When a motor (not illustrated) is driven to operate the pump, the rotational movement of the motor is changed to the reciprocating movement of a diaphragm shaft 111 by devices such as an eccentric cam, and thereby the diaphragm 110 is driven back and forth. FIG. 1A illustrates a state of the diaphragm being driven back, that is, a suction process, and FIG. 1B illustrates a state of the diaphragm being driven forward, that is, a discharge process.
During the suction process, due to the internal pressure, each check ball 140 of the suction side and the discharge side moves toward the center of the pump head 100. Subsequently, since there is the opening-side valve seat 141 is formed at the end of the suction hole 105 of the pump head 100, liquid is drawn to the pump chamber 130 through the cross-shaped groove. And, the discharge hole 106 is closed by the check ball 140. On the other hand, during the discharge process, each check ball 140 moves away from the pump head 100 to the outside such that the suction hole 105 is closed and only the discharge hole 106 is opened. Subsequently, the liquid in the pump chamber 130 is discharged through the cross-shaped groove formed at the discharge-side connector 160.
The advantage of such a conventional diaphragm pump in the long term is that the average amount of the discharged liquid is very constant. However, since the pumping operation is separated into the suction process and the discharge process, and it is intermittently performed, there is a fundamental problem of a pulsation of the discharged liquid, as shown in FIG. 1D.
In order to prevent such a pulsation of the discharged liquid, two or more pumps are connected in parallel and operated in different strokes, as shown in FIG. 1E. Referring to FIG. 2, another method is explained. By installing an air chamber 200 at the center of a liquid pipe passage, during the discharge process, the air in the air chamber 200 is pressurized, and thereby the amount of the discharging liquid from a discharge pipe 210 is reduced. During the suction process, due to the expansion force of the pressurized air, the liquid stored in the air chamber 200 during the discharge process is discharged through the discharge pipe 210. For reference, the unmentioned reference numeral 201 is a pressure gauge.
However, the benefit of using two more pumps being connected in parallel is significantly offset by the substantial increase in installation cost. Moreover, in the case of installing the air chamber at the center of the liquid pipe passage, it is difficult to perform the installation operation. Also, it is unsuitable to establish the air chamber when the connector of the pump or the liquid pipe passage is made of tube type. Furthermore, damages to the connector caused by the vibration of the air chamber when operating the pump are frequently occurred. Furthermore, since such methods cannot fundamentally remove the pulsation of the discharged liquid, water hammering caused by the pulsation can be generated and it may destroy pipes, especially, at high pressure.